The DOAC ‐ FRAIL Study—Same Dose, Different Story: Prevalence of Deviant Direct Oral Anticoagulant Levels in Nursing Home Residents

BACKGROUND: Direct oral anticoagulants (DOACs) are prescribed using fixed dosing regimens, despite limited evidence on their pharmacokinetic behavior in nursing home residents. PARTICIPANTS AND SETTING: One hundred nursing home residents are receiving apixaban, rivaroxaban, dabigatran, or edoxaban in multiple long-term care facilities in the Netherlands. METHODS: In this prospective observational study, DOAC peak levels were measured 2-4 h post-dose during routine laboratory testing. Levels were classified as below, within, or above the expected on-therapy range. Logistic regression analyses identified factors associated with peak levels outside the expected on-therapy range. RESULTS: Overall, 40% of residents had DOAC peak levels outside the expected on-therapy range; 32% were above and 8% were below. In univariable analyses, above-range levels were associated with lower renal function, apixaban use, and history of myocardial infarction, but none remained independently associated after multivariable adjustment. Below-range levels were associated with preserved renal function and rivaroxaban use; analyses for below-range levels were limited to univariable analyses due to the small number of events. CONCLUSION: A substantial proportion of nursing home residents exhibited DOAC peak levels outside the expected on-therapy range despite guideline-concordant dosing. These findings highlight the complexity of anticoagulant management in frail older adults residing in long-term care and support the need for careful clinical reassessment of DOAC therapy in this population.